I'll tell you why Riot think Zeds a Healthy Assassin
HE CAN"T KILL MORE THEN ONE TARGET EVERY 80 SECONDS (At MAX rank that is). Every other assassin has resets or massive aoe to do it. Zed is limited to 1 target and one target only unless hes godly fed 10 and 0 in lane. Then i Almost 100% gurantee that Zed is never going to kill you by himself. Without his ult.
Talon has a massive aoe ult that can hit an entire team twice if use correctly. He also has insane single target burst.
Leblanc has and aoe w that does godly damage has 2 jumps. Her ult is on a very low cd for how much it does. Allowing her to constantly kill you.
Akali has resets if she gets a kill, and can stack her ult 3 times, and sit in her shroud to wait for CD's.
Katarina does AOE q, AOE w, Single Target E, HUGE AOE Ult. Short cd Ult, and has resets.
Fizz has relatively long CD's early game, late game though his ult is on a 46-50 second CD. He doesn't really need his ult AS much as zed to kill someone, since he has sustained damage with W. Though after his recent nerfs he does require his ult a bit more to get that full burst.
Nidalee is 100% reliant on landing her Q spear, if she doesn't land it, dont ever expect to die to her. She can't run at you with cougar (Unless your someone like Mordekaiser , but even then Mordekaiser would just kill you soon as you jumped) She has quite a low CD on her Q though it has a 90 Mana cost. But she can constantly get kills every 3-5 seconds. As long as she lands the spear since he R resets.
Kha'zix has resets on his jumps to jump from person to person if he gets a kill and quite a short CD on her Q.
Master Yi has resets, and another reset passive, and huge AA damage because of how he builds, he's also very hard to run away from because of his Movespeed and resistent to slows.
Rengar And Shaco are the only ones i think wouldn't qualify for the constantly getting kills and resets, as with the rest of the ones i've listed.
This is the reason why Riot thinks Zed is healthy, because Zed is by definition the only one out of the assassin who is an ACTUAL assassin, everyone else has huge burst, resets, AOE damage, etc. I know Zed is annoying to play against and can be frustrating for the player, but Zed only brings one thing to a team, and thats' 1 single target HUGE burst (not instant, and easily countered) he's more just annoying to play against in lane cause of how safe Zed is to farm, and poke. But thats about it. His split pushing got nerfed. So he has WAVE CLEAR (Requires he put himself at risk though by using his entire combo besides R, long CD on W) Very limited in who he can kill, if someone has Zhonya's it can completely destroys Zed. And don't give me that bullshit of "But i shouldn't be forced to build Zhonya's" Well that SUCKS, your SUPPOSE to be be itemizing against the champion your playing, if your against a dam kalista as a tank then you should build a freaking Thorn Mail or Frozen heart. Because of how much attack speed she has. Idk why people cry about having to build Zhonya's, you build it anyways or should if your against any other ad assassin if not your stupid. It gives a huge amount of AP, armor , and an amazing active, that just so happens TO BE THE PERFECT COUNTER, for Zed, You should be freaking HAPPY that their is an ITEM, that 100% nulls a champions combo. No other champion is 100% just Nulled because of 1 item. Talon can just e to you and if you Zhonya's just wait it out and then kill you right after.
I really do not know why people complain about having to build Zhonya's against Zed, its the only AP Armour item you'd be stupid not to (Except Iceborn Guantlet but thats not really worth on a mage). No ones forcing you to build it, but it preety much ruins Zed. Why would you not build an item that just completely destroys a champion? Hell if their was an item that could completely nullify riven then i'd freaking build it. I wouldn't have to stack Frozen Heart, Iceborn Guantlet, Randuins, Sunfire Cape, JUST so I don't get 100-0 as Nasus. Even then she can still itemize against my build to null it. With Zed zhonya's passive just ruins him, and you should be happy it does. Don't go crying about having to build Zhonya's against an AD assassin. Until RIOT makes a new AP Armour item for mages. Your stuck with Zhonya's, don't be bitching when RIOT gives you a dam free win in a duel against Zed, arguably the best duelist in the game.
Tl;Dr Zeds healthy because to wave clear he must use his Q W E. For full clear, and w has long CD. He's limited to ONE person to kill every 80 seconds, unless he's super fed and outplays the shit out of you and 1v2's. Though thats your own fault. He gets completely nullified by Zhonya's He can't constantly kill, like every other assassin in the game (Besides Rengar and Shaco)
,
, and
are healthy, which they don't. They outright called those three unhealthy for EXACTLY the reason you're saying they think Zed is healthy.
He'd like to have a word with you one what Riot considers healthy deletion.
is someone you definitely don't want to Zhonya's against, because you're just giving him time to charge his Q. Low mobility bruisers love it when you Zhonya's.
and
also counter his ult. (which mean, with zhonyas, only tanks and support are pretty much 100% sure targets, and tank usually have too much armor and hp to be an ideal target, which only leave the support, whom might get zhonya or be overall tanky depending which one it is lol.)